Device enhancement of hydroxyquinloine-based organic light-emitting diodes using a uniformly mixed electron transporting host

Abstract

By engineering a new cohosting system of tris(8-hydroxyquinoline) and 4,7-diphenyl-1,10-phenanthroline in the electron transport layer, the current efficiency of the organic light emitting diode is improved by more than 20% while the bias is reduced by ∼40% as compared to the device with a single host of Alq 3 as the electron transport layer. The maximum luminance is over 16000 cd/m 2 at the bias of 22V and the current of 475mA/cm 2, which is ∼73% higher than the single host Alq 3 device without optimizing the layer thickness. The lifetime under ambient environment is enhanced by a factor of ∼1.8. The reasons for the improvement will be investigated. The results strongly indicate that the knowledge of bulk conductivity engineering of organic n-type transporters shows practical significance in OLED applications.